(1) Field of the Invention
The invention described herein relates to an improved computer mouse comprising a frame that houses a ball coupled to mechanical or optical encoders that, in combination, produce signals indicative of X (horizontal) and Y (vertical) movement as the frame is moved in any direction along a flat surface.
(2) Description of the Prior Art
Present day computer mouse assemblies provide an output signal in serial (RS-232) or parallel ("bus mouse") form to a computer for the purpose of moving a cursor along a display screen, selecting a menu, selecting an item within a menu, etc. These present day assemblies also incorporate a plurality of switches that output a specific code that the computer software interprets as an "escape", "enter", etc. In all prior art computer mouse assemblies, the resolution settings of the internal encoders are fixed; i.e., moving the frame in a given direction for a fixed distance always results in the same number of output pulses or dots per inch (dpi). This situation is particularly disadvantageous if a large computer monitor (normally a Cathode Ray Tube (CRT)) is used. A 100 dot per inch (dpi) mouse needs a surface area of 12 by 8 inches to cover a 1,200 by 800 pixel or "dot" resolution CRT monitor. Computer mouse manufacturers have attempted to overcome this deficiency by loading a software program into the computer's memory that allows an operator, by using the mouse and a keyboard, to modify the resolution of the mouse. This process is normally referred to as dynamic or ballistic tracking. These software adjustment programs normally require over 30,000 bytes of resident computer memory. Utilizing a resolution adjustment program when the computer is executing a word processing program, for example, would result in approximately fifteen fewer standard 81/2.times.11 inch pages for the word processed text file.
Some manufacturers, such as Dexxa International, have devised a mouse resolution program that generates a tone using the computer's internal speaker to indicate the resolution setting of the mouse. This approach, like other prior art solutions, also requires the use to an internal memory resident dynamic tracking adjustment program and a keyboard for adjusting the mouse's X,Y resolution settings. Furthermore, if the computer is located very far from the operator, the audio tones may not be heard.
All prior art solutions utilizing a memory resident resolution adjustment program require that the operator depress keys on the computer keyboard, such as CTRL and ALT, in addition to depressing a key or keys on the mouse. This approach is particularly disadvantageous since it always requires keyboard entry. In addition to the above, a number of commercially available software programs operate totally on mouse generated data without the need for keyboard entries. However, these software programs do not provide for resolution adjustment.
U.S. patent applications Ser. No. 146,743 and Ser. No. 146,744, by the present inventor, filed concurrently on Jan. 15, 1988 describe a switch display encoder apparatus and rate aided sensing system for interactively adjusting and displaying encoder speed and resolution parameters. This type of computer mouse is particularly useful for Computer Aided Design (CAD) and Computer Aided Manufacturing (CAM) applications since it provides adjustment of resolution settings based on speed of the mouse. The principal disadvantage of this invention is that the computer mouse assembly must incorporate additional switches and numeric displays beyond the ones normally found on industry standard computer mouse assemblies. Mechanically integrating six switches with numeric displays would result in a significant increase in the overall size of the mouse assembly. Another disadvantage is that an operator must divert his/her attention from the computer screen to view the numerical displays on the mouse assembly indicating the newly adjusted resolution settings. This type of mouse assembly also requires a minimum of 60 signal connections to an external sensing system in order to function properly. Finally, this type of computer mouse may appear too inhibiting or sophisticated for a word processing operator or an individual who is not "computer literate".